1. Field of the Invention
The present invention relates to a copper-zinc alloy for semi-finished materials and articles which are highly loaded or stressed and subjected to extreme wear, in particular materials for synchronizing rings.
A high load-carrying capability, in effect, durability, a high coefficient of friction and a high resistance to wear are characterizing parameters which are of particular significance with regard to synchronizing rings utilized in motor vehicle or automotive transmissions. A high coefficient of friction is of importance in the effectuation of fast and precise gear shifting; in essence, to enable a comfortable shifting, and a high degree of resistance to wear is of importance from the standpoint of the service life of the synchronizing ring.
Because of the progressively increasing power of motor vehicle or automotive engines, the demands which are placed on synchronizing rings are similarly increasing. However, in view of the increasing pressure on costs encountered in the manufacture of such synchronizing rings, there arises more frequently the query as to whether the coatings of molybdenum which are applied in many instances in view of the resistance to wear thereof could not be eliminated through the use of an improved alloy.
2. Description of the Prior Art
In essence, the present invention represents an improvement over an alloy as described in the German Patent No. 37 35 783, which is commonly assigned to the assignee of the present application. Pursuant to the German patent, the therein disclosed alloy comprises about 50 to 65% copper, 1 to 6% aluminum, 0.5 to 5% silicon, 5 to 8% nickel and selectively 0 to 1% iron, 0 to 2% lead, with the balance being zinc. In the foregoing alloy, the nickel is present predominantly in an intermetallic compound with silicon in the form of nickel silicides which are distributed uniformly and finely in a rounded-off form.